Transformerless On-Site Generation

ABSTRACT

Methods and apparatuses for electrolysis that does not require the use of a transformer to operate. The apparatus comprises one or more electrolytic cells which comprise the number of intermediate electrodes sufficient to enable the cell or cells to operate at the rectified line voltage without any need for voltage regulation, or near the rectified line voltage with only some voltage regulation, such as less than 20% of the rectified line voltage. Such regulation is achieved by using a buck or boost converter rather than a transformer, and can be varied to accommodate fluctuations in the line voltage and/or conductivity of the electrolyte, or varied to produce different chemistries in the same apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of the filing ofU.S. Provisional Patent Application Ser. No. 61/710,468, entitled“Transformerless On-Site Generation”, filed on Oct. 5, 2012, thespecification and claims of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention (Technical Field)

The present invention is apparatus and configuration for providing powerto one or more electrolytic cells without requiring a large transformerto take incoming AC voltage to a lower DC voltage. This innovation is asubstantial cost and footprint improvement over other electrolytic celldesigns.

2. Background Art

Electrolytic cells of either mono-polar or bi-polar configuration foron-site generation (OSG) of oxidants are typically arranged inelectrically parallel configurations. Voltages used for a mono-polarcell typically vary from 3.5-6.0 Volts plate to plate. Bipolarelectrolytic cells often have somewhat higher voltages, but they aretypically run at DC voltages of 9.0-42.0 Volts. A switching DC powersupply, or transformer coupled with other devices (diodes, SCRs,capacitors, etc) is typically used to take the available incoming ACvoltage(s) (for example 110V, 220V, 400V, 480V, 600V) to provide aconstant, lower DC voltage at the cell. This methodology/apparatus ofstepping down the voltage has substantial disadvantages. The cost ofgoods sold (COGS) associated with the step down voltage apparatus aretypically a substantial part of the overall cost of the on-sitegenerator (often 10-50%). Stepping down voltage also results insubstantial power losses, increasing the operating cost of generatingoxidants or other chemicals on-site and creating more heat, which mustsomehow be dealt with by cooling fans, etc. Lastly, the footprint andweight associated with the apparatus used to step down the voltage is asubstantial part of the overall footprint and weight (typically 10-45%).

SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)

An embodiment of the present invention is an apparatus comprising one ormore electrolytic cells comprising a number of intermediate electrodessufficient to enable the apparatus to operate within only a percentageof a rectified line voltage while maintaining a desired plate to platevoltage between adjacent intermediate electrodes, the apparatus notcomprising a transformer. The apparatus is optionally designed tooperate at approximately the rectified line voltage, the apparatus notcomprising any voltage regulation. The apparatus preferably comprisesvoltage regulation provided by a buck converter circuit or a boostconverter circuit. The voltage regulation can preferably vary a voltageacross the one or more electrolytic cells up to approximately eightypercent of the rectified line voltage, more preferably up toapproximately fifty percent of the rectified line voltage, even morepreferably up to approximately twenty-five percent of the rectified linevoltage, and most preferably up to approximately twenty percent of therectified line voltage. If more than one electrolytic cells are used,they are preferably connected in series. The apparatus preferablyfurther comprises a plurality of contactors in an H-bridge configurationfor reversing the polarity of the one or more electrolytic cells inorder to enable self-cleaning of the one or more electrolytic cells.

Another embodiment of the present invention is a method for performingelectrolysis, the method comprising rectifying incoming line voltage;providing one or more electrolytic cells comprising a number ofintermediate electrodes sufficient to enable the one or moreelectrolytic cells to operate within only a percentage of a rectifiedline voltage while maintaining a desired plate to plate voltage betweenadjacent intermediate electrodes; and either not varying the rectifiedline voltage or varying the rectified line voltage without using atransformer. If the rectified line voltage is not varied it is becausethe number of intermediate electrodes is sufficient to enable the one ormore electrolytic cells to operate at approximately the rectified linevoltage. If the rectified line voltage is varied, varying the rectifiedline voltage is preferably performed using a buck converter circuit or aboost converter circuit. Varying the rectified line voltage preferablycomprises varying a voltage across the one or more electrolytic cells upto approximately eighty percent of the rectified line voltage, morepreferably up to approximately fifty percent of the rectified linevoltage, even more preferably up to approximately twenty-five percent ofthe rectified line voltage, and most preferably up to approximatelytwenty percent of the rectified line voltage. Varying the rectified linevoltage optionally accommodates fluctuations in the incoming linevoltage or changes the chemical products, for example the quantity ofhydrogen and hypochlorite to hydrogen peroxide ratio, produced by theone or more electrolytic cells. Varying the rectified line voltageoptionally comprises accommodating a varying conductivity ofelectrolyte, such as that produced by fluctuations in salinity and/ortemperature of seawater. If a plurality of cells is used, the methodpreferably comprises connecting them in series. The method preferablyfurther comprises reversing the polarity of the one or more electrolyticcells using a plurality of contactors in an H-bridge configuration,thereby self-cleaning the one or more electrolytic cells. Varying therectified line voltage using a boost converter circuit preferablycomprises harvesting energy from a low voltage power source or matchinga solar array output to a desired voltage across the one or moreelectrolytic cells.

Objects, advantages and novel features, and further scope ofapplicability of the present invention will be set forth in part in thedetailed description to follow, taken in conjunction with theaccompanying drawings, and in part will become apparent to those skilledin the art upon examination of the following, or may be learned bypractice of the invention. The objects and advantages of the inventionmay be realized and attained by means of the instrumentalities andcombinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate an embodiment of the present inventionand, together with the description, serves to explain the principles ofthe invention. The drawings are only for the purpose of illustratingvarious embodiments of the invention and are not to be construed aslimiting the invention. In the drawings:

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a circuit diagram of the embodiment of FIG. 1 also comprisinga filter capacitor.

FIG. 3 is a circuit diagram of the embodiment of FIG. 2 furthercomprising an H-bridge circuit to perform reverse polarity cleaning ofthe cell or cells.

FIG. 4 is a circuit diagram of the embodiment of FIG. 3 furthercomprising a buck converter.

FIG. 5 is a circuit diagram of the embodiment of FIG. 3 furthercomprising a boost converter.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the invention are methods and apparatuses to providepower to one or more electrolytic cells. The apparatuses take anincoming power of one type and convert it to power suitable to drive abank or line of electrolytic cells arranged electrically in seriesand/or a single large bi-polar electrolytic cell designed to handle thehigh voltages.

In the simple embodiment of the present invention shown in FIG. 1,incoming AC power 10 is passed through fuse 30 and, via contactorcontrol 20, diode rectifier 40 and is then applied to a bipolar cell ora plurality of electrolytic cells 50, the latter preferably arranged inseries, which typically cannot use conventional AC power directly. Thediode rectifier turns the alternating current (AC) into a wavy directcurrent (DC). The effective DC voltage on the cell or cell line isapproximately 1.4×VAC. Thus, for multiple cells, N electrolytic cellsdesigned to operate at 1/N×(1.4×VAC), each with plate to plate voltagesbetween intermediate electrodes from 3.5-7V, are preferably arrangedelectrically in series allowing for elimination of the transformer.

FIG. 2 is a similar embodiment, in which incoming AC power 60 is passedthrough fuse 80, diode rectifier 90 via contactor control 70, and filtercapacitor 95, which smoothes out the wavy DC voltage, which is thenapplied to a bipolar cell or a plurality of electrolytic cells 100.

FIG. 3 is a schematic of another embodiment of the present inventionthat comprises contactors (i.e. switches and/or relays) arranged in anH-bridge configuration to reverse the polarity to clean the electrolyticcells (preferably for a short time and/or at lower currents). IncomingAC power 110 is passed through fuse 130 diode rectifier 140 viacontactor control 120, and filter capacitor 145, and is then applied toa bipolar cell or a plurality of electrolytic cells 150. Relays 151,152, 153, 154 are preferably arranged in an H-bridge configuration andare controlled by forward polarity signal 156 and reverse polaritysignal 158.

The circuit in FIG. 4 uses a buck converter in addition to theconfiguration of FIG. 3. Incoming AC power 160 is passed through fuse180 diode rectifier 190 via contactor control 170, and filter capacitor195, and is then applied to a bipolar cell or a plurality ofelectrolytic cells 200. Relays 201, 202, 203, 204 are preferablyarranged in an H-bridge configuration and are controlled by forwardpolarity signal 206 and reverse polarity signal 208. The buck converter,by means of altering the Pulse Width Modulation (PWM) signal 210 ofMOSFET switch 220 provides an efficient way to step the voltage downfrom the rectified mains. Buck converter also preferably comprises diode230, filter capacitor 240, and inductor 250.

Using a buck converter or similar circuit has certain advantages overusing a transformer to step down voltage, as is typical for existingsystems. First, a voltage can be selected that is appropriate for theelectro- chemistry required by the user. That is, by using differentelectrode to electrode voltages, different chemistries can be achieved.For example, hydrogen production can be increased or decreased, orhypochlorite production can be favored over hydrogen peroxide (or viceversa).

Second, the present invention can more easily compensate for thedifferent mains voltages found throughout the world. Manufacturingindustrial equipment for the international market requires the equipmentto utilize different AC mains voltages. Three phase power throughout theworld can be any of 208, 220, 230, 240, 346, 380, 400, 415, 480, 600, or690 VAC at 50-60 Hz. Normally this requires special transformersdesigned for a specific range of voltages or step up/down transformersused in conjunction with a standard transformer designed for operationof the cell line at a specific set voltage. A typical example is that ofa transformer primary designed to utilize 480 VAC mains and a rectifiedsecondary that produces 42 VDC. If this transformer were to be connectedto a 380 VAC main the rectified output would be 33.3 VDC, which would betoo low to drive the cell line. A step up transformer of at least thesame power rating and approximately the size would be required to beinstalled at the site in addition to the standard system. This cansubstantially increase the overall cost and footprint of the installedsystem. There is also a decrease in overall power efficiency due tocoupling losses of two transformers.

Third, if sea water is used as the sole brine feedstock to the system,the power supply must adjust to the conductivity of the sea waterdynamically, since the conductivity of seawater varies by salinity andtemperature and is not constant. The buck configuration can use currentfeedback instead of voltage and thus become a constant current sourceinstead. This is difficult or impossible to implement usingtransformers.

Because a transformerless circuit, such as one comprising a buckconverter, cannot typically step down more than 100% of the rectifiedline voltage (and typically less, such as less than 80%, less than 50%,less than 25%, or even less than 20%), it is preferable that theelectrolytic cell or cells are designed to accommodate close to therectified line voltage without any voltage regulation. In other words,the cell or cells are preferably configured with the number ofintermediate electrodes that enable the system to operate with voltageregulation of exactly, or alternatively only a percentage of, therectified line voltage to operate at the desired plate to plate voltagein each cell. This typically means the cell or cells operate at a muchhigher overall voltage than typical cells in the art, and typicallycomprise a larger number of intermediate electrodes in order to achievethe desired plate to plate voltage. For multiple cells this is easier toaccomplish when the cells are arranged in series rather than inparallel.

Another embodiment of the invention is shown in FIG. 5. A boostconverter is used to step up a lower voltage from battery 310 to avoltage suitable to drive a cell (preferably bipolar) or cell line 320.The boost converter preferably is operated via PWM signal 300 andcomprises inductor 330, diode 340, and Mosfet 350. Optonal filtercapacitor 360 smoothes out the voltage. Relays 370, 375, 380, 385 arepreferably arranged in an H-bridge configuration and are controlled byforward polarity signal 390 and reverse polarity signal 395. Thisconfiguration provides a way to harvest energy from, for example, just afew solar cells or small human powered generators that can be used topower small portable water treatment equipment. This configuration canalso be used to optimize larger off the grid applications that utilizephotovoltaic energy generation by better matching the output of solararray to the required cell line.

EXAMPLE

A single mono-polar (two electrodes) cell capable of producing fivepounds of chlorine a day with a cell voltage of 5 volts required a cellcurrent of 100 amps. In Table 1, a five pound system is scaled up inthree different configurations to produce 675 pounds of chlorine a daywith a 480 volt three phase input (VAC). Thus the rectified line voltagewas approximately 672 V. The plate to plate voltage for eachconfiguration was 5 volts. The first two configurations use conventionalmethods. The last one uses a series cell approach (the cells areconnected in series) that is matched to the incoming power available. Inthis case if N=3 then we would have three electrolytic cells in the cellline, each with 45 chambers.

TABLE 1 Incoming Cell Cell Transformer Cell Bus Cell Power VoltageCurrent Diode Transformer Weight Bar Size Configuration (Kilowatts)(VDC) (Amps) Losses (%) Loss (%) (Pounds) (sq inch) Single Parallel108.9 5 13500 23 15 1330 13.5 Primary Cell Series Parallel 86.5 40 16887 15 1057 1.7 Series 67.8 675 100 .5 0 0 0.1

Although the invention has been described in detail with particularreference to the disclosed embodiments, other embodiments can achievethe same results. Variations and modifications of the present inventionwill be obvious to those skilled in the art and it is intended to coverall such modifications and equivalents. The entire disclosures of allpatents and publications cited above are hereby incorporated byreference.

What is claimed is:
 1. An apparatus comprising one or more electrolyticcells comprising a number of intermediate electrodes sufficient toenable the apparatus to operate within only a percentage of a rectifiedline voltage while maintaining a desired plate to plate voltage betweenadjacent intermediate electrodes; said apparatus not comprising atransformer.
 2. The apparatus of claim 1 designed to operate atapproximately the rectified line voltage, said apparatus not comprisingany voltage regulation.
 3. The apparatus of claim 1 comprising voltageregulation provided by a buck converter circuit or a boost convertercircuit.
 4. The apparatus of claim 3 wherein said voltage regulation canvary a voltage across said one or more electrolytic cells up toapproximately eighty percent of the rectified line voltage.
 5. Theapparatus of claim 4 wherein said voltage regulation can vary a voltageacross said one or more electrolytic cells up to approximately fiftypercent of the rectified line voltage.
 6. The apparatus of claim 5wherein said voltage regulation can vary a voltage across said one ormore electrolytic cells up to approximately twenty-five percent of therectified line voltage.
 7. The apparatus of claim 6 wherein said voltageregulation can vary a voltage across said one or more electrolytic cellsup to approximately twenty percent of the rectified line voltage.
 8. Theapparatus of claim 1 wherein a plurality of electrolytic cells isconnected in series.
 9. The apparatus of claim 1 further comprising aplurality of contactors in an H-bridge configuration for reversing thepolarity of said one or more electrolytic cells in order to enableself-cleaning of said one or more electrolytic cells.
 10. A method forperforming electrolysis, the method comprising: rectifying incoming linevoltage; providing one or more electrolytic cells comprising a number ofintermediate electrodes sufficient to enable the one or moreelectrolytic cells to operate within only a percentage of a rectifiedline voltage while maintaining a desired plate to plate voltage betweenadjacent intermediate electrodes; and not varying the rectified linevoltage or varying the rectified line voltage without using atransformer.
 11. The method of claim 10 wherein the rectified linevoltage is not varied because the number of intermediate electrodes issufficient to enable the one or more electrolytic cells to operate atapproximately the rectified line voltage.
 12. The method of claim 10wherein varying the rectified line voltage is performed using a buckconverter circuit or a boost converter circuit.
 13. The method of claim12 wherein varying the rectified line voltage comprises varying avoltage across the one or more electrolytic cells up to approximatelyeighty percent of the rectified line voltage.
 14. The method of claim 13wherein varying the rectified line voltage comprises varying a voltageacross the one or more electrolytic cells up to approximately fiftypercent of the rectified line voltage.
 15. The method of claim 14wherein varying the rectified line voltage comprises varying a voltageacross the one or more electrolytic cells up to approximatelytwenty-five percent of the rectified line voltage.
 16. The method ofclaim 15 wherein varying the rectified line voltage comprises varying avoltage across the one or more electrolytic cells up to approximatelytwenty percent of the rectified line voltage.
 17. The method of claim 10wherein varying the rectified line voltage accommodates fluctuations inthe incoming line voltage.
 18. The method of claim 10 wherein varyingthe rectified line voltage changes the chemical products produced by theone or more electrolytic cells.
 19. The method of claim 18 wherein thechemical products are selected from the group consisting of quantity ofhydrogen and hypochlorite to hydrogen peroxide ratio.
 20. The method ofclaim 10 wherein varying the rectified line voltage comprisesaccommodating a varying conductivity of electrolyte.
 21. The method ofclaim 20 wherein the electrolyte comprises seawater and the conductivityof the seawater varies due to fluctuations in salinity and/ortemperature of the seawater.
 22. The method of claim 10 comprisingconnecting a plurality of electrolytic cells in series.
 23. The methodof claim 10 further comprising reversing the polarity of the one or moreelectrolytic cells using a plurality of contactors in an H-bridgeconfiguration, thereby self-cleaning the one or more electrolytic cells.24. The method of claim 12 further wherein varying the rectified linevoltage using a boost converter circuit comprises harvesting energy froma low voltage power source or matching a solar array output to a desiredvoltage across the one or more electrolytic cells.